2WIL

AGED FORM OF HUMAN BUTYRYLCHOLINESTERASE INHIBITED BY TABUN ANALOGUE TA5

Summary for 2WIL

• Entry DOI: 10.2210/pdb2wil/pdb
• Related: 1EHO 1EHQ 1KCJ 1P0I 1P0M 1P0P 1P0Q 1XLU 1XLV 1XLW 2J4C 2WID 2WIF 2WIG 2WIJ 2WIK
• Descriptor: CHOLINESTERASE, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[alpha-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose, ethylphosphoramidic acid, ... (7 entities in total)
• Functional Keywords: aging, hydrolase, inhibition, polymorphism, glycoprotein, serine esterase, disease mutation
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 2
• Total formula weight: 123554.10

Authors

Carletti, E.,Aurbek, N.,Gillon, E.,Loiodice, M.,Nicolet, Y.,Fontecilla, J.,Masson, P.,Thiermann, H.,Nachon, F.,Worek, F. (deposition date: 2009-05-12, release date: 2009-05-26, Last modification date: 2024-10-16)

Primary citation

Carletti, E.,Aurbek, N.,Gillon, E.,Loiodice, M.,Nicolet, Y.,Fontecilla, J.,Masson, P.,Thiermann, H.,Nachon, F.,Worek, F.
Structure-Activity Analysis of Aging and Reactivation of Human Butyrylcholinesterase Inhibited by Analogues of Tabun
Biochem.J., 421:97-, 2009

PubMed Abstract: hBChE [human BChE (butyrylcholinesterase)] naturally scavenges OPs (organophosphates). This bioscavenger is currently in Clinical Phase I for pretreatment of OP intoxication. Phosphylated ChEs (cholinesterases) can undergo a spontaneous time-dependent process called 'aging' during which the conjugate is dealkylated, leading to creation of an enzyme that cannot be reactivated. hBChE inhibited by phosphoramidates such as tabun displays a peculiar resistance to oxime-mediated reactivation. We investigated the basis of oxime resistance of phosphoramidyl-BChE conjugates by determining the kinetics of inhibition, reactivation (obidoxime {1,1'-(oxybis-methylene) bis[4-(hydroxyimino) methyl] pyridinium dichloride}, TMB-4 [1,3-trimethylene-bis(4-hydroxyiminomethylpyridinium) dibromide], HLö 7 {1-[[[4-(aminocarbonyl) pyridinio]methoxy]methyl]-2,4-bis-[(hydroxyimino)methyl] pyridinium dimethanesulfonate)}, HI-6 {1-[[[4-(aminocarbonyl) pyridinio] methoxy] methyl]-2-[(hydroxyimino)methyl]pyridinium dichloride monohydrate} and aging, and the crystal structures of hBChE inhibited by different N-monoalkyl and N,N-dialkyl tabun analogues. The refined structures of aged hBChE conjugates show that aging proceeds through O-dealkylation of the P(R) enantiomer of N,N-diethyl and N-propyl analogues, with subsequent formation of a salt bridge preventing reactivation, similarly to a previous observation made on tabun-ChE conjugates. Interestingly, the N-methyl analogue projects its amino group towards the choline-binding pocket, so that aging proceeds through deamination. This orientation results from a preference of hBChE's acyl-binding pocket for larger than 2-atoms linear substituents. The correlation between the inhibitory potency and the N-monoalkyl chain length is related to increasingly optimized interactions with the acyl-binding pocket as shown by the X-ray structures. These kinetics and X-ray data lead to a structure-activity relationship that highlights steric and electronic effects of the amino substituent of phosphoramidate. This study provides the structural basis to design new oximes capable of reactivating phosphoramidyl-hBChE conjugates after intoxication, notably when hBChE is used as pretreatment, or to design BChE-based catalytic bioscavengers.

PubMed: 19368529
DOI: 10.1042/BJ20090091

Experimental method

X-RAY DIFFRACTION (3.1 Å)